Hydrocyanation catalyst systems, particularly pertaining to the hydrocyanation of olefins, are well known in the art. For example, systems useful for the hydrocyanation of butadiene to form pentenenitrile (PN) and in subsequent hydrocyanation of pentenenitrile (PN) to form adiponitrile (ADN), are known in the commercially important nylon synthesis field. The hydrocyanation of olefins using transition metal complexes with monodentate phosphite ligand is well documented in the prior art. See for example; U.S. Pat. Nos. 3,496,215, 3,631,191, 3,655,723, and 3,766,237, and Tolman, C. A.; McKinney, R. J.; Seidel, W. C.; Druliner, J. D.; and Stevens, W. R.; Advances in Catalysis, 33, 1, 1985. The hydrocyanation of activated olefins, such as with conjugated olefins (e.g., butadiene and styrene) and strained olefins (e.g., norbornene), proceeds without the use of a Lewis Acid promoter, while hydrocyanation of unactivated olefins, such as 1-octene and 3-pentenenitrile, requires the use of a Lewis Acid promoter. Teachings regarding the use of a promoter in the hydrocyanation reaction appear, for example, in U.S. Pat. No. 3,496,217. This patent discloses an improvement in hydrocyanation using a promoter selected from a large number of metal cation compounds with a variety of anions as catalyst promoters. U.S. Pat. No. 3,496,218 discloses a nickel hydrocyanation catalyst promoted with various boron-containing compounds, including triphenylboron and alkali metal borohydrides. U.S. Pat. No. 4,774,353 discloses a process for the preparation of dinitriles, including ADN, from unsaturated nitriles, including PN, in the presence of a zero-valent nickel catalyst and a triorganotin catalyst promoter. U.S. Pat. No. 4,874,884 discloses a process for producing ADN by the zero-valent nickel catalyzed hydrocyanation of pentenenitriles in the presence of a synergistic combination of promoters selected in accordance with the reaction kinetics of the ADN synthesis.
Bidentate phosphite ligands are useful ligands in the hydrocyanation of activated olefins. See, for example: Baker, M. J., and Pringle, P. G.; J. Chem. Soc., Chem. Commun., 1292, 1991; Baker, M. J.; Harrison, K. N.; Orpen, A. G.; Pringle, P. G.; and Shaw, G.; J. Chem. Soc.; Chem. Commun., 803, 1991, Union Carbide, WO 93,03839.
U.S. Pat. No. 5,175,335 to Casalnuovo et al. discloses the use of chiral, nonracemic, bidentate phosphinite ligands for the enantioselective hydrocyanation of aromatic vinyl compounds. The nickel-catalyzed hydrocyanation of these substrates occurs in a predominantly Markownikoff fashion. At Column 19, the '335 Patent shows Compound "F," a bidentate diphosphinite and shows its use in the hydrocyanation of 2-vinylnaphthalene.